Photoacoustic endoscopic imaging system and method based on polarized light multi-angle rotation scanning

Abstract

This invention provides a photoacoustic endoscopic imaging system and method based on multi-angle rotation scanning of polarized light, belonging to the field of photoacoustic imaging technology. It includes a control system, a light source system, an optical path system, an endoscope probe, a data acquisition system, and a data reconstruction system. The control system is connected to both the light source system and the data acquisition system. The light source system, optical path system, and endoscope probe are connected sequentially. The data acquisition system is connected to both the endoscope probe and the data reconstruction system. The optical path system includes at least a hollow servo motor and a half-wave plate. The hollow servo motor responds to a timing pulse signal to control the half-wave plate to rotate multiple preset angles to adjust the polarization direction of linearly polarized light. This invention, employing a combination of a hollow servo motor and a half-wave plate, can quickly and accurately adjust the polarization direction of light, achieving multi-angle scanning, significantly improving imaging speed, and enabling the acquisition of multiple images in a shorter time. It is suitable for clinical scenarios requiring real-time feedback.

Description

Technical Field

[0001] This invention relates to the field of photoacoustic imaging technology, and in particular to a photoacoustic endoscopic imaging system and method based on multi-angle rotation scanning of polarized light. Background Technology

[0002] Photoacoustic imaging is an emerging medical imaging technique that combines optical and ultrasonic technologies to achieve high-resolution and high-contrast imaging. Currently, there are two main methods for photoacoustic imaging: photoacoustic tomography (PACT) and photoacoustic microscopy. PACT is suitable for imaging larger tissue volumes and provides high depth resolution; however, in biological tissues with severe light scattering, image quality is easily affected, leading to blurred images. Photoacoustic microscopy, on the other hand, offers even higher spatial resolution and is suitable for imaging minute structures, but it has limitations in imaging depth, unable to penetrate deeper tissues.

[0003] Traditional photoacoustic imaging systems typically employ a single-wavelength laser source. While a 1200 nm laser can effectively excite photoacoustic signals in biological tissues, its imaging speed and quality remain limited when processing complex tissues. Due to the scattering characteristics of light in biological tissues, signal attenuation and distortion significantly increase noise interference during the imaging process, reducing the accuracy and reliability of the final image. Furthermore, existing technologies generally require long scan times, limiting their real-time performance and adaptability in clinical applications, especially in surgical scenarios requiring rapid response, where they often cannot provide timely imaging feedback. Summary of the Invention

[0004] This invention provides a photoacoustic endoscopic imaging system and method based on polarized light multi-angle rotation scanning, which solves the defects of existing photoacoustic imaging systems that require long scanning time and cannot provide timely imaging feedback, significantly improving the speed, resolution and signal quality of biological tissue imaging, and meeting the needs of real-time clinical imaging.

[0005] In a first aspect, the present invention provides a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning, comprising a control system, a light source system, an optical path system, an endoscope probe, a data acquisition system, and a data reconstruction system. The control system is connected to the light source system and the data acquisition system respectively. The light source system, the optical path system, and the endoscope probe are connected in sequence. The data acquisition system is connected to the endoscope probe and the data reconstruction system respectively.

[0006] The control system is used to generate timing pulse signals and control the light source system, the optical path system and the data acquisition system according to the timing pulse signals.

[0007] The light source system is used to respond to the timing pulse signal, generate a pulsed laser beam of a preset wavelength, convert the pulsed laser beam into linearly polarized light, and emit it.

[0008] The optical path system includes at least a hollow servo motor and a half-wave plate. The hollow servo motor is used to respond to the timing pulse signal and control the half-wave plate to rotate by multiple preset angles to adjust the polarization direction of the linearly polarized light.

[0009] The endoscope probe is used to process the light beam emitted from the half-wave plate, transmit the processed light beam to the sample, receive the photoacoustic signal fed back by the sample, and convert it into an electrical signal.

[0010] The data acquisition system is used to respond to the timing pulse signal, acquire the electrical signal, process the electrical signal, and transmit the processed electrical signal to the data reconstruction system;

[0011] The data reconstruction system is used to generate sample images based on the received processed electrical signals.

[0012] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided. The preset angles include 0°, 22.5°, 45° and 67.5°. The optical path system further includes an optical fiber coupler and an optical fiber collimator. The optical fiber coupler and the optical fiber collimator are used to couple and collimate the linearly polarized light into the optical fiber. Correspondingly, the hollow servo motor is used to control the half-wave plate to rotate between the four preset angles and adjust the polarization direction of the linearly polarized light in the optical fiber.

[0013] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided. The endoscope probe includes a MEMS scanning micromirror, a focusing lens, a rod lens group, an objective lens group, a light-transmitting reflector, and an ultrasonic transducer disposed in the endoscope housing. The MEMS scanning micromirror is used to rapidly modulate and switch the light beam emitted from the half-wave plate to adjust the beam path and intensity. The focusing lens is used to focus the light beam output by the MEMS scanning micromirror, and the optical parameters of the focusing lens are determined based on the characteristics of the sample. The rod lens group is used to adjust the propagation direction and shape of the light beam output by the focusing lens. The objective lens group is used to perform secondary focusing on the light beam output by the rod lens group. The light-transmitting reflector is used to transmit the light beam output by the objective lens group to the sample and receive the photoacoustic signal fed back by the sample. The ultrasonic transducer is used to convert the photoacoustic signal into an electrical signal.

[0014] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided, wherein the focusing lens is an aspherical lens, the rod lens group includes several rod lenses arranged at equal intervals and with multiple layers of coating, the objective lens group includes several objective lenses with multiple layers of coating and anti-reflective coating, and the endoscope shell has a double-layer structure, the inner layer being a flexible material and the outer layer being a rigid structure.

[0015] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided, wherein the light source system comprises a 1200 nm pulsed laser and a linear polarizer, wherein the 1200 nm pulsed laser is used to generate a pulsed laser beam with a wavelength of 1200 nm in response to a timing pulse signal, and the linear polarizer is used to convert the pulsed laser beam into linearly polarized light.

[0016] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided. The data reconstruction system is further used to analyze the sample image and quantify the optical properties of the sample in different directions. The control system is further used to adjust the timing pulse signal according to the optical properties in order to adjust the parameters of the pulsed laser beam.

[0017] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided, wherein the sample is placed in a sample cell, the sample cell is used to provide a dynamic environment for the sample through the flow of a fluid medium or a gas medium, and the sample cell is also provided with a temperature detection unit and a pressure detection unit, which are used to provide different experimental environments for the sample according to the detection data of the temperature detection unit and the pressure detection unit respectively.

[0018] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided, wherein the endoscope probe, the data acquisition system and the data reconstruction system are connected by a high-speed data transmission interface.

[0019] According to the present invention, a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning is provided, wherein the input end of the data acquisition system is further connected to a signal amplifier and a shock-absorbing bracket for fixing the signal amplifier, and the signal amplifier is used to amplify the electrical signal and output it to the data acquisition system.

[0020] Secondly, the present invention also provides a photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning, implemented based on any one of the photoacoustic endoscopic imaging systems based on polarized light multi-angle rotation scanning, the method comprising:

[0021] In response to a timing pulse signal, a pulsed laser beam of a preset wavelength is generated, and the pulsed laser beam is converted into linearly polarized light and emitted.

[0022] The polarization direction of the linearly polarized light is adjusted by using a half-wave plate that switches between multiple preset angles;

[0023] The beam emitted from the half-wave plate is processed, and the processed beam is transmitted to the sample. The photoacoustic signal fed back by the sample is received and converted into an electrical signal.

[0024] In response to the timing pulse signal, the electrical signal is acquired, processed, and analyzed to generate a sample image.

[0025] This invention provides a photoacoustic endoscopic imaging system and method based on polarized light multi-angle rotation scanning. It adopts a combination of hollow servo motor and half-wave plate, which can quickly and accurately adjust the polarization direction of light to achieve multi-angle scanning, significantly improve the imaging speed, and acquire multiple images in a shorter time. It is suitable for clinical scenarios that require real-time feedback. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a circuit diagram of the photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning provided by the present invention.

[0028] Figure 2 This is a schematic diagram of the preset angle of the half-wave plate provided by the present invention and the polarization direction corresponding to the preset angle.

[0029] Figure 3 This is a side view of the hollow servo motor and half-wave plate provided by the present invention.

[0030] Figure 4 This is a three-dimensional structural diagram of the hollow servo motor and half-wave plate provided by the present invention.

[0031] Figure 5 This is a schematic flowchart of the photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning provided by the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] It should be noted that in the description of this invention, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The terms "upper," "lower," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The terms "first," "second," etc., used in this invention are used to distinguish similar objects, not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, a first object can be one or more. Furthermore, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0035] All actions involving the acquisition of signals, information, or data in this invention are carried out in compliance with the relevant data protection laws and regulations of the locality and with authorization from the owner of the relevant device.

[0036] The following description, in conjunction with the accompanying drawings, describes a photoacoustic endoscopic imaging system and method based on polarized light multi-angle rotation scanning provided by the present invention.

[0037] Figure 1 This is a circuit diagram of the photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning provided by the present invention, as shown below. Figure 1 As shown, this invention provides a photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning, including a control system 1, a light source system, an optical path system, an endoscope probe, a data acquisition system, and a data reconstruction system. The control system 1 is connected to both the light source system and the data acquisition system. The light source system, the optical path system, and the endoscope probe are connected sequentially. The data acquisition system is connected to both the endoscope probe and the data reconstruction system. These systems are connected via optical fibers, optical components, or electronic signal lines to ensure efficient information transmission and processing. The light source system is fixed at the top of the device, the optical path system is located at the center, the endoscope probe extends to the detection area, and the data acquisition system and data reconstruction system are located on the operating table for easy user operation and monitoring.

[0038] The control system 1 is used to generate timing pulse signals and control the light source system, the optical path system and the data acquisition system according to the timing pulse signals.

[0039] The light source system is used to respond to the timing pulse signal, generate a pulsed laser beam of a preset wavelength, convert the pulsed laser beam into linearly polarized light, and emit it.

[0040] The optical path system includes at least a hollow servo motor 6 and a half-wave plate 7. The hollow servo motor 6, in response to the timing pulse signal, controls the half-wave plate 7 to rotate by multiple preset angles to adjust the polarization direction of the linearly polarized light. By controlling the rotation speed and angle of the half-wave plate 7, the hollow servo motor 6 rapidly changes the polarization state of the light beam, optimizing the imaging effect on the sample. The hollow servo motor 6 is connected to the half-wave plate 7 and driven by the control system 1, ensuring that the motor's movement can precisely control the angle of the half-wave plate 7, allowing for rapid switching between several preset fixed positions, thus changing the polarization direction of the linearly polarized light accordingly, thereby affecting the light's penetration and scattering behavior in the sample.

[0041] The endoscope probe is used to process the light beam emitted from the half-wave plate 7, transmit the processed light beam to the sample 14, receive the photoacoustic signal fed back by the sample, and convert it into an electrical signal. Optionally, the light beam emitted from the half-wave plate 7 is incident on the endoscope probe through the reflector 8 in order to reduce the size of the endoscope probe.

[0042] The data acquisition system is used to respond to the timing pulse signal, acquire the electrical signal, process the electrical signal, and transmit the processed electrical signal to the data reconstruction system. The data acquisition system includes an acquisition card 17, which converts the analog signal in the electrical signal into a digital signal for subsequent processing.

[0043] The data reconstruction system is used to generate sample images based on the received processed electrical signals. The data reconstruction system can be configured as a computer PC 18. A data acquisition system is connected to the endoscope probe, receives its output electrical signals, and converts the received analog signals into digital signals for subsequent processing. The converted digital signals are transmitted to the computer PC via a high-speed interface for further processing. The computer PC 18 receives the digital signals from the data acquisition system and analyzes them using data processing software.

[0044] As an optional embodiment, the half-wave plate 7 is made of a single-crystal material with high optical quality to ensure that it does not cause light scattering or distortion when rotating at high speed, thereby ensuring that the direction change of the polarized light is accurate and stable.

[0045] As an optional embodiment, the data reconstruction system is further used to analyze the sample image and quantify the optical properties of the sample in different directions. The control system 1 is also used to adjust the timing pulse signal according to the optical properties in order to adjust the parameters of the pulsed laser beam. The control system 1 adopts a real-time feedback mechanism, which can automatically adjust the parameters of the laser beam and the scanning speed according to the characteristics of the sample to optimize the imaging effect.

[0046] This invention utilizes timing pulse signals generated by control system 1 to achieve unified and precise control of the light source system, optical path system, and data acquisition system, reducing errors between these systems. Control system 1 can be constructed using an FPGA board, receiving rotation angle commands from a host computer. The hollow servo motor 6 is equipped with a high-precision encoder that monitors the rotation angle in real time and transmits feedback signals to control system 1. Control system 1 adjusts the current via PWM to drive the motor to the target angle and uses a closed-loop control mechanism to ensure precise motor rotation, achieving high-precision control with an angle error of less than 0.1°. This invention employs precise feedback and a closed-loop control mechanism, significantly improving the accuracy of angle conversion and contributing to more precise control of polarized light and higher final imaging resolution.

[0047] Specifically, the rotation of the hollow servo motor 6 is achieved through the cooperation of a host computer and a slave computer. Parameters such as the target angle and target speed are input into the host computer interface, and commands are sent to the slave FPGA via serial port. The slave computer converts the target angle into a rotation signal for the servo motor and controls its rotation. The motor encoder monitors the rotation angle in real time and feeds back the actual position to the slave computer. The slave computer corrects errors to ensure accurate positioning.

[0048] The specific control process of the lower-level machine: The FPGA generates a PWM signal with a certain duty cycle (pulse width ratio);

[0049] The frequency of the PWM signal determines the motor speed, and the duty cycle determines the output current intensity. After receiving the PWM signal, the driver converts it into motor coil current to drive the motor to rotate. The FPGA generates a series of pulse signals with a fixed frequency. Each pulse drives the motor to rotate by a basic step angle (the basic step angle is determined by the motor manufacturing process and physical characteristics). By adjusting the number and frequency of pulses, the total rotation angle and speed can be controlled.

[0050] Pulse count calculation: Target pulse count = Target angle * Encoder resolution / 360°

[0051] In addition, the encoder returns the current angle in real time (in terms of pulse count); the FPGA compares the actual pulse count with the target pulse count and dynamically adjusts the drive signal.

[0052] It is understood that the present invention uses a combination of a hollow servo motor 6 and a half-wave plate 7, which can quickly and accurately adjust the polarization direction of light, realize multi-angle scanning, significantly improve imaging speed, and acquire multiple images in a shorter time, making it suitable for clinical scenarios that require real-time feedback.

[0053] Based on the above embodiments, as an optional embodiment, the light source system includes a 1200nm pulsed laser 2 and a linear polarizer 3. The 1200nm pulsed laser 2 is used to generate a pulsed laser beam with a wavelength of 1200 nm in response to a timing pulse signal, and the linear polarizer 3 is used to convert the pulsed laser beam into linearly polarized light.

[0054] Optionally, the 1200nm pulsed laser 2 has a high peak power, typically 500 mW, capable of rapidly exciting photoacoustic signals in biological tissues. Furthermore, the laser is fixed to a light source support to ensure its stability during emission. The linear polarizer 3 is used to convert the laser beam into linearly polarized light, increasing the coherence of the light. This polarizer is connected to the laser via an optical clamp, and its angle is adjustable to adapt to different experimental requirements; it is fixed at the entrance of the optical path system.

[0055] It is understood that the linear polarizer 3 provided by this invention has the characteristics of high light transmittance and low optical distortion, so as to maximize the imaging quality. This invention takes into account the characteristics of different samples and can adapt to different imaging needs by changing different types of linear polarizer 3, half-wave plate 7 and lens combination.

[0056] Figure 2 This is a schematic diagram of the preset angle of the half-wave plate 7 provided by the present invention and the polarization direction corresponding to the preset angle, as shown below. Figure 2 As shown, based on the above embodiments, as an optional embodiment, the preset angles include 0°, 22.5°, 45°, and 67.5°. These four angles are the angles at which the motor drives the half-wave plate to rotate, corresponding to the four desired output light polarization states (0°, 45°, 90°, and 135°). Light with different polarization angles exhibits different absorption or scattering behaviors when passing through tissue. By acquiring photoacoustic signals at polarization angles of 0°, 45°, 90°, and 135°, the optical anisotropy information of the sample in different directions can be revealed. 0° and 90° represent the limiting states of horizontal and vertical polarization, respectively, while 45° and 135° represent the oblique states of linear polarization; they are diagonal states in the horizontal and vertical directions. These four angles can provide the maximum degree of optical property variation, covering the characteristics of all major polarization directions within the sample. One of the main applications of polarized light is through fitting polarization parameters, such as birefringence parameters and extinction rates. By combining photoacoustic signals from 0°, 45°, 90°, and 135°, polarization characteristics, such as phase delay caused by polarization-dependent absorption or birefringence, can be reconstructed. These four angles provide a complete sample of the linear polarization state, facilitating subsequent calculations of polarization information using Malus's law or other polarization analysis models. Choosing 0°, 45°, 90°, and 135° allows for maximum information coverage with fewer angles, reducing system complexity while ensuring measurement accuracy. Too many angles increase the difficulty of data processing, while too few angles may fail to fully represent the optical properties of the sample.

[0057] The optical path system also includes an optical fiber coupler 4 and an optical fiber collimator 5. The optical fiber coupler 4 and the optical fiber collimator 5 are used to couple and collimate the linearly polarized light into the optical fiber. Correspondingly, the hollow servo motor 6 is used to control the half-wave plate 7 to rotate between four preset angles to adjust the polarization direction of the linearly polarized light in the optical fiber.

[0058] Fiber optic coupler 4 and fiber optic collimator 5 effectively couple and collimate the laser, employing high-quality fiber optic coupler 4 and collimator to minimize optical loss. Fiber optic coupler 4 and fiber optic collimator 5 are secured at the front end of the optical path system and connected to the laser and linear polarizer 3 via single-mode fiber.

[0059] The focal length of this invention is 50 mm, ensuring that the beam can propagate in parallel. The hollow servo motor 6, model HO3507, is a key component and possesses high-precision control capabilities. The motor is installed at the center of the optical path system, driving the rotation of the half-wave plate 7 to ensure the stability of the beam during rotation. The half-wave plate 7, fixed to the motor's output shaft, is 1 mm thick and made of optical quartz. The rotation angle range of the half-wave plate 7 is 0° to 67.5°, and its main function is to adjust the polarization direction of the incident light, allowing the beam to enter the probe at different angles. The rotation of the motor is adjusted in real time by the motor control system 1.

[0060] Figure 3 This is a side view of the hollow servo motor 6 and the half-wave plate 7 provided by the present invention. Figure 4 This is a three-dimensional structural diagram of the hollow servo motor 6 and the half-wave plate 7 provided by the present invention, as shown below. Figure 3 and Figure 4 As shown, the hollow servo motor 6 is configured within the optical path system to drive the rapid rotation of the half-wave plate 7. Furthermore, the motor's output shaft is connected to the mounting base of the half-wave plate 7 via a dedicated bearing to ensure smooth rotation and prevent vibration. The half-wave plate 7 is used to adjust the polarization direction of the incident light, enabling multi-directional scanning of the sample. The half-wave plate 7 is fixed to the 3D support 19 and secured to the motor's output shaft with screws (e.g., four M2 screws) to ensure smooth movement during motor rotation and precise angle adjustment capability.

[0061] This invention utilizes a rotational scanning method to ensure complete imaging of samples at multiple polarization angles, including 0°, 45°, 90°, and 135°, thus improving sample coverage. Compared to single-angle imaging, it can more comprehensively display the morphology and internal structural features of the sample. Rotational scanning allows for the acquisition of photoacoustic signals at different polarization angles, enabling the analysis of the sample's optical anisotropy, which is particularly suitable for detecting the optical properties of fibrous tissues. This design can accurately reveal the differences in optical characteristics within the sample in different directions, providing more sample information. Through multiple rotational scans, the system can image the same target area multiple times, improving the signal-to-noise ratio and resolution of the images. This multi-angle imaging technology enhances the presentation of sample details, making it particularly suitable for the identification and analysis of complex microstructures. The system acquires multi-angle images of the sample through rotational scanning at different angles and performs 3D reconstruction by image overlay, accurately displaying the sample's three-dimensional structure. Through optical scanning at different polarization angles, the system can quantify the optical properties of the sample in various directions, such as absorption and scattering coefficients. This quantitative analysis provides more information for assessing tissue health, and is particularly suitable for optical property analysis in disease diagnosis.

[0062] As an optional embodiment, the control system 1 provided by this invention integrates artificial intelligence algorithms, which can automatically adjust system parameters according to sample characteristics and imaging results to improve the intelligence and adaptability of imaging. The processing algorithm adopts a deep learning model to improve the feature extraction capability of complex samples and enhance the analysis accuracy of imaging data. The control system 1 is also used to rapidly image multiple samples and integrate their data, using image stitching technology to generate high-resolution composite images for a more comprehensive analysis of sample characteristics.

[0063] The impact of different polarization directions on the algorithm for generating sample images is mainly reflected in image processing, optical property extraction, and multi-dimensional information fusion.

[0064] 1. When light with different polarizations enters a sample, it interacts with the sample's microstructures (such as collagen fibers, muscle fibers, and cell membranes), causing different optical changes, such as absorptivity, scattering characteristics, birefringence, and polarization retention. These changes reflect the differences in the sample's microstructure and composition, and are important bases for imaging algorithm analysis.

[0065] 2. The intensity of photoacoustic imaging signals in different polarization directions varies due to the anisotropy of the optical properties within the sample. The algorithm needs to analyze the signal differences at each polarization angle and optimize image contrast to highlight optical properties in specific directions, such as the orientation and absorption characteristics of collagen fibers.

[0066] 3. Photoacoustic images from multiple polarization angles may exhibit spatial displacement or angular deviation. The algorithm requires image registration to accurately overlay images from each angle. Subsequently, image fusion technology is used to integrate the information from each angle into a single high-resolution, multi-dimensional composite image, thereby improving the overall imaging performance.

[0067] The photoacoustic imaging algorithm of the image processing part of the present invention includes decoupling of polarized photoacoustic signals, quantitative analysis of polarization characteristics, image reconstruction and fusion, and generation of polarization characteristic maps. It can fuse and process photoacoustic data from multiple polarization angles and generate high-resolution imaging data, thereby extracting optical characteristic information of the sample.

[0068] 1. Decoupling of polarized photoacoustic signals

[0069] Using photoacoustic signals with different polarization angles (0°, 45°, 90°, 135°), the total photoacoustic signal can be decomposed into polarization-dependent and polarization-independent components. The definitions are as follows:

[0070]

[0071] in: It is a photoacoustic signal at a certain polarization angle θ. It is a polarization-dependent photoacoustic signal component. It is a photoacoustic signal component that is independent of polarization.

[0072] 2. Quantitative analysis of polarization characteristics

[0073] Introducing the polarization contrast parameter ):

[0074]

[0075] This parameter reflects the change in photoacoustic response of the sample under different polarization angles, and quantitatively describes the anisotropic characteristics of the sample.

[0076] 3. Image Reconstruction and Fusion

[0077] For each polarization angle of the photoacoustic signal Preliminary image reconstruction is performed using traditional photoacoustic imaging reconstruction algorithms (such as Delay-and-Sum, DAS).

[0078]

[0079] in: It is the reconstruction intensity corresponding to position r. It is a weighting function (which can be set according to distance or signal-to-noise ratio). It is signal i at the corresponding time The value of .

[0080] After obtaining images from different angles, a composite image is obtained through a polarization spectral fusion algorithm:

[0081]

[0082] in: It is a weighting factor for the polarization angle, which can be determined according to... Dynamic adjustments are made to enhance regions with significant polarization characteristics.

[0083] 4. Generation of polarization characteristic diagrams

[0084] Based on the images at each polarization angle, a polarization direction map (PDM) is generated:

[0085]

[0086] This figure shows the main polarization response directions at various locations of the sample, providing a visual representation of the sample's anisotropy distribution.

[0087] Compared with existing photoacoustic imaging algorithms, this invention has the following advantages:

[0088] 1. Decoupling processing of polarization-dependent components has been added, which improves the ability to extract anisotropic information of samples.

[0089] 2. Combining polarization contrast and orientation characteristics, a polarization spectrum fusion algorithm for image post-processing has been added.

[0090] 3. A polarization direction characteristic diagram is provided, which can intuitively reflect the polarization response of the microstructure inside the sample.

[0091] In this way, the present invention can more comprehensively analyze the optical properties of biological tissues, especially the orientation and density distribution of collagen fibers.

[0092] It is understood that this invention rapidly images the sample four times from multiple polarization angles (0°, 45°, 90°, 135°) and optimizes image quality through algorithmic registration. The imaging data from each polarization angle carries different optical characteristic information, fusing multi-angle imaging with polarization information. Computer image processing algorithms fuse and stitch these multi-angle imaging data to generate a high-resolution image with richer optical characteristics (such as polarization information). The multi-angle polarization imaging technology provided by this invention can more comprehensively and accurately characterize the anisotropy and optical properties of the sample. Furthermore, the imaging of this invention is not based solely on ordinary photoacoustic signals but combines polarized light information, extracting the optical characteristics of the sample through specific algorithms, adding an additional dimension of polarization data, and providing innovative data support for the detailed analysis of the sample's internal structure and optical properties. By introducing the fusion processing of multi-angle polarization information and a dedicated image processing algorithm, this invention achieves significant technological innovations in image quality, information extraction, and processing speed.

[0093] This invention achieves the following functions:

[0094] 1. Automated rotation angle adjustment: Compared with manual or simple motor-driven systems, this invention achieves automated motor control through the collaborative work of the host computer and the slave computer, reducing errors caused by human intervention and improving the ease of use of the equipment.

[0095] 2. Multi-angle polarization control: In existing technologies, motors can only drive a fixed angle, while this system can achieve multi-angle adjustment through software control, especially multiple different polarization angles, making the beam control more flexible and providing richer optical information for imaging.

[0096] 3. Full-angle coverage: The system covers polarization directions of 0°, 45°, 90° and 135° through four imaging at different angles, which can more comprehensively obtain the anisotropic optical properties of the sample, while existing technologies may only cover a single or limited polarization angle range.

[0097] 4. Automated control logic: Existing systems often require manual adjustment or multi-component collaboration to adjust the optical path. However, this system reduces complex physical adjustments and improves the smoothness of the imaging process through automatic control between the host computer and the motor.

[0098] 5. Enhanced Sample Analysis Capabilities: By utilizing the polarization changes in four imaging phases, the system can effectively detect and quantify differences in the optical properties of samples in different directions. This is difficult to achieve with simple beam modifications in existing technologies, greatly expanding the system's application range and detection depth.

[0099] Based on the above embodiments, as an optional embodiment, the endoscope probe includes a MEMS scanning micromirror 9, a focusing lens 10, a rod lens group 11, an objective lens group 12, a light-transmitting reflector 13, and an ultrasonic transducer 15 disposed in the endoscope housing.

[0100] The MEMS scanning micromirror 9 is used to rapidly modulate and switch the light beam emitted from the half-wave plate 7 to adjust the beam path and intensity; it enables high-speed beam adjustment. By controlling the MEMS scanning micromirror 9, the path and intensity of the light can be changed. The MEMS scanning micromirror 9 is located at the rear end of the optical path system, before the focusing lens 10. It receives the modulated beam from the light source system and transmits the modulated beam to the focusing lens 10. The MEMS scanning micromirror 9 is used to quickly adjust the scanning range and is located downstream of the optical path system. This component achieves real-time response through a micromechanical system, is connected to the optical lens, and is fixed by a lightweight bracket to reduce interference with the optical path.

[0101] The focusing lens 10 is used to focus the light beam output by the MEMS scanning micromirror 9. The optical parameters of the focusing lens 10 are determined based on the characteristics of the sample. The focusing lens 10 focuses the modulated light beam onto the sample, ensuring that the beam effectively illuminates the target area, thereby improving the resolution and contrast of the image. The focusing lens 10 is located behind the MEMS scanning micromirror 9 and receives the light beam from it. Its optical parameters (such as focal length) need to be selected according to the sample characteristics to ensure optimal focusing effect. Beam profile detection is commonly used in experiments: a beam analyzer or camera is used to detect the beam profile to ensure that the shape, size, and uniformity of the beam after focusing meet the experimental requirements. This method helps optimize the focal length of the lens and the collimation effect of the beam by accurately measuring the intensity distribution and shape of the beam. The focusing lens 10 uses high-quality optical glass with a focal length of 15 mm to ensure that the beam is focused on the detection area. The lens is connected to the optical path system via optical fiber and fixed to the front of the probe.

[0102] The rod lens group 11 is used to adjust the propagation direction and shape of the light beam output by the focusing lens 10. The rod lens group 11 adjusts the propagation direction and shape of the light beam, improves the uniformity and focusing quality of the beam, corrects any deviations in the optical path, and ensures stable beam transmission. The rod lens group 11 is located after the focusing lens 10 and receives the focused light beam. The rod lens group 11 is used to further adjust the direction and propagation of the light beam, while the objective lens group 12 is responsible for forming the final image.

[0103] The objective lens group 12 is used to refocus the beam output from the rod lens group 11; the objective lens group 12 is responsible for further focusing and imaging the beam, providing the required magnification and resolution to capture sample details and form high-quality images. The objective lens group 12 is located after the rod lens group 11 and directly receives the optimized beam. The objective lens group 12 is designed with a magnification of 10× to ensure the acquisition of clear tissue images.

[0104] The transmissive reflector 13 is used to transmit the light beam output from the objective lens group 12 to the sample and to receive the photoacoustic signal fed back from the sample. The transmissive reflector 13 allows the laser beam to pass smoothly, ensuring that the light signal required for imaging can be effectively transmitted to the sample, while reflecting the photoacoustic signal from the sample to ensure that these signals can be effectively transmitted to the ultrasonic transducer 15. Located after the objective lens group 12, the transmissive reflector 13 directly receives the light beam focused by the objective lens group 12, and its reflective surface reflects the photoacoustic signal generated by the sample to the ultrasonic transducer 15, enabling it to effectively receive and convert it into an electrical signal. The transmissive reflector 13 is used to reflect acoustic signals while transmitting light signals. It is mounted at the front end of the probe and is linearly connected to the focusing lens 10 to maximize light transmittance. This lens has high reflectivity and transmittance to ensure signal quality.

[0105] The ultrasonic transducer 15 is used to convert the acoustic signal into an electrical signal. The main function of the ultrasonic transducer 15 is to receive photoacoustic signals and convert them into electrical signals. These signals are used for data acquisition and subsequent image reconstruction. The ultrasonic transducer 15 is directly connected to the reflected light path of the transparent acoustic mirror 13 and connected to the data acquisition system to achieve real-time signal processing. The ultrasonic transducer 15 is fixed to the transparent acoustic mirror 13 by adhesive bonding and is responsible for converting the acoustic signal into an electrical signal. This component operates at a frequency of 5 MHz and can effectively capture changes in sound waves within tissue.

[0106] The focusing lens 10, the rod lens group 11, and the objective lens group 12 are jointly responsible for focusing the light signal and forming a clear image. They are precisely positioned and fixed by a laser alignment device and adjusting screws to ensure that high-resolution images can be obtained in tissues at different depths.

[0107] The light-transmitting and sound-reflecting mirror 13 simultaneously transmits light signals and reflects sound signals, enhancing signal acquisition efficiency. This mirror is installed at the front end of the endoscope probe and is connected to the optical system and ultrasonic transducer 15 via an optical bracket to ensure its stability during the imaging process.

[0108] The ultrasonic transducer 15 is used to receive photoacoustic signals and convert them into electrical signals. The transducer is fixed to the appropriate position of the probe by gluing or threading to ensure that it can effectively capture acoustic signals.

[0109] The endoscope housing provides structural support and protection, ensuring the stability and reliability of the internal optical components.

[0110] As an optional embodiment, the focusing lens 10 is an aspherical lens, which can precisely control the focusing point of lasers of different wavelengths, reduce spherical aberration and chromatic aberration, and improve the clarity of sample imaging. The rod lens group 11 includes several rod lenses arranged at equal intervals and with multi-layer coatings to reduce light loss and improve the stability and uniformity of beam transmission. The objective lens group 12 includes several multi-layer coated objectives with anti-reflective coatings to reduce interference from multiple internal reflections on imaging. The light-transmitting and acoustic mirror 13, through a photoacoustic lens structure at a specific angle, can simultaneously improve the transmittance of light and the reflection efficiency of acoustic signals, thereby improving the photoacoustic signal acquisition effect. The endoscope shell has a double-layer structure, with a flexible inner layer and a rigid outer layer. It is durable and flexible to operate, and has heat dissipation channels to ensure heat dissipation during long-term operation.

[0111] It is understood that the endoscopic probe provided by this invention has a small and compact structure, suitable for detection in confined spaces. The probe integrates high-precision optical components such as a focusing lens 10, a rod lens group 11, and an objective lens group 12, and achieves efficient transmission of photoacoustic signals through a light-transmitting and reflecting mirror 13, ensuring high-resolution endoscopic imaging quality. The system uses a motor to precisely control the rotation of the half-wave plate 7 to achieve multi-angle scanning, making it particularly suitable for complex endoscopic applications, enabling high-resolution imaging in the body or inaccessible tissues, thus improving diagnostic accuracy. This endoscopic system, through optimized optical path design, ensures that light is effectively transmitted even in complex internal environments. The system achieves efficient transmission and, through the cooperation of the transparent reflector 13 and the ultrasonic transducer 15, realizes efficient reflection and acquisition of photoacoustic signals, generating clear endoscopic images. The endoscopic imaging system of this invention uses polarized light technology to perform anisotropic analysis of tissues, enhancing the ability to identify the optical properties of tissues. It is particularly suitable for quantitative analysis of optical properties in different directions in confined endoscopic environments, providing rich diagnostic information. The endoscopic system uses a motor to precisely control the rotation of the half-wave plate 7 to achieve multi-angle polarized light imaging, which can adapt to the complex endoscopic imaging needs of different tissue structures, improving the flexibility and accuracy of imaging.

[0112] Based on the above embodiments, as an optional embodiment, the sample is placed in a sample cell. The sample cell provides a dynamic environment for the sample through the flow of a fluid or gas medium. The sample cell is also equipped with a temperature detection unit and a pressure detection unit, used to provide different experimental environments for the sample based on the detection data from the temperature detection unit and the pressure detection unit, respectively. Specifically, the intensity and frequency of the pulsed laser beam can be adjusted to optimize the irradiation conditions on the sample, thereby achieving the best photoacoustic signal response.

[0113] The sample cell is designed to allow the flow of fluid or gaseous media to image samples under dynamic conditions, thereby improving the real-time monitoring capability of biological samples or chemical reaction processes. In addition, the sample cell is designed with temperature and pressure monitoring functions to adjust experimental conditions in real time and ensure the stability of sample imaging.

[0114] Based on the above embodiments, as an optional embodiment, the endoscope probe, the data acquisition system, and the data reconstruction system are connected via a high-speed data transmission interface. This ensures real-time acquisition and processing of photoacoustic signals and reduces data transmission latency. The control system 1 of the hollow servo motor 6 is implemented by a host computer through the following detailed process: The host computer is connected to the motor drive module via an interface such as USB, RS-232, or Ethernet. Typically, the drive module supports the UART communication protocol for easy transmission of control signals. The user inputs control parameters on the host computer interface, such as the target rotation angle (0°, 22.5°, 45°, 67.5°) and rotation speed. The host computer generates corresponding control commands based on the user-input parameters. These commands include the frequency and duty cycle of the PWM signal, used to control the motor's speed and direction. The host computer sends the generated control commands to the motor drive module via a serial port or network. The drive module parses the commands and generates motor control signals. The motor drive module adjusts the motor's rotation angle and speed according to the received signals, and the hollow servo motor 6 begins to rotate at the set angle.

[0115] Based on the above embodiments, as an optional embodiment, the input terminal of the data acquisition system is further connected to a signal amplifier 16 and a shock-absorbing bracket for fixing the signal amplifier 16. The signal amplifier 16 is used to amplify the electrical signal and output it to the data acquisition system.

[0116] The data acquisition system is used to perform analog-to-digital conversion on the received electrical signals. It should have a high sampling rate and high resolution to meet the requirements of real-time imaging. A high-precision acquisition card 17 with 16-bit analog-to-digital conversion capability can be selected to quickly process the signals transmitted from the ultrasonic transducer 15. Its connection method is USB interface, which facilitates connection with a computer PC 18. The acquisition card 17 is fixed in the data processing unit to ensure a stable connection with the signal amplifier 16.

[0117] The signal amplifier 16 is used to enhance signal strength to improve the signal-to-noise ratio. It has a good gain range and bandwidth to adapt to different types of signals. The amplifier is connected to the acquisition card 17 via a cable and is fixed with a shock-absorbing bracket to prevent external interference.

[0118] The PC (computer terminal) 18 is equipped with a high-performance processor and large memory, receiving data from the acquisition card 17 in real time. Software functions include image stitching, registration, and post-processing, employing advanced image processing algorithms to achieve efficient data analysis. Users operate through an intuitive graphical interface. The PC 18 is responsible for real-time data processing and image reconstruction, possessing high processing power and large memory to support complex image processing algorithms. Its main functions include receiving signals from the acquisition card 17, stitching, registering, and post-processing multiple acquired images to generate a high-quality composite image.

[0119] Furthermore, the computer PC 18 can also perform image analysis, extract tissue structure information, and provide a user-friendly interface for monitoring and operation. Through a high-speed data transmission interface, it ensures a stable connection with the signal amplifier 16, realizes real-time imaging feedback and data recording, and further enhances the practicality and flexibility of the system.

[0120] In summary, the present invention has the following advantages:

[0121] 1. Compared to traditional photoacoustic endoscopy systems, this invention employs a combination of a hollow servo motor 6 and a half-wave plate 7, enabling rapid and precise adjustment of the light polarization direction for multi-angle scanning. This design significantly improves imaging speed, allowing for the acquisition of multiple images in a shorter time, making it suitable for clinical scenarios requiring real-time feedback. Furthermore, the flexible configuration of the MEMS scanning micromirror 9 component allows for rapid adjustment of the scanning range, further enhancing the system's response speed in various applications. This real-time capability enables physicians to make diagnoses more quickly, optimizing clinical decisions, and providing significant convenience, especially in emergency situations.

[0122] 2. This invention optimizes the optical path system design, combining the precise layout of the focusing lens 10, rod lens group 11, and objective lens group 12 to ensure efficient beam focusing and image clarity. Compared to existing technologies, this system effectively reduces light scattering and loss during imaging, thereby improving image resolution. Furthermore, the combined design of the transmissive acoustic mirror 13 and the ultrasonic transducer 15 ensures effective acoustic signal capture, improving signal quality and reliability. This high signal-to-noise ratio imaging result helps to more accurately identify the microstructure of tissues, improving the detection capability of lesion areas, which is particularly important for clinical applications.

[0123] 3. The design of this invention fully considers the flexibility and scalability of the system. Through modular design, the various parts (light source system, optical path system, endoscope probe, and data acquisition and reconstruction system) can be flexibly combined and configured according to different application requirements. The control system 1 integrates advanced data processing functions, which can not only monitor the operating status of each part in real time, but also support complex image processing and analysis tasks. This highly integrated design can reduce the size and weight of the equipment, improve patient comfort, and facilitate doctors' operation in the clinical environment. In addition, the open design of the system allows for future upgrades or expansions to adapt to emerging medical technology needs, ensuring that the system remains competitive in the rapidly evolving medical field.

[0124] The photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning provided by the present invention is described below. The photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning described below can be referred to in correspondence with the photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning described above.

[0125] Figure 5 This is a schematic flowchart of the photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning provided by the present invention, as shown below. Figure 5 As shown, the present invention provides a photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning, implemented based on any of the photoacoustic endoscopic imaging systems based on polarized light multi-angle rotation scanning, and the method includes the following steps.

[0126] In step S100, in response to a timing pulse signal, a pulsed laser beam of a preset wavelength is generated, and the pulsed laser beam is converted into linearly polarized light and emitted. Specifically, a laser beam with a wavelength of 1200 nm is emitted, and the laser beam is converted into linearly polarized light by a linear polarizer to ensure high contrast of the beam during subsequent imaging. The linearly polarized light is coupled and collimated into the optical path system to ensure that the beam propagation path is clear and undistorted.

[0127] Step S200 involves adjusting the polarization direction of the linearly polarized light using a half-wave plate that switches between multiple preset angles. The half-wave plate changes the polarization state of the linearly polarized light, and can rapidly switch between 0°, 22.5°, 45°, and 67.5°, providing various polarization states. A hollow servo motor is used to rapidly rotate the half-wave plate to achieve laser beams with different polarization angles, improving the imaging quality of the sample.

[0128] Step S300: The laser beam emitted from the half-wave plate is processed, and the processed beam is transmitted to the sample. The photoacoustic signal fed back from the sample is received and converted into an electrical signal. The laser beam is focused onto the sample cell to irradiate the sample to be tested; the photoacoustic signal generated by the sample is received and converted into an electrical signal.

[0129] In step S400, in response to the timing pulse signal, the electrical signal is acquired and processed and analyzed to generate a sample image. The electrical signal is processed and analyzed using a computer PC to generate high-resolution imaging data of the sample and extract relevant optical characteristic information of the sample.

[0130] The photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning provided by this invention has the same technical effects as the photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning, which will not be elaborated further.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning, characterized in that, It includes a control system, a light source system, an optical path system, an endoscope probe, a data acquisition system, and a data reconstruction system. The control system is connected to the light source system and the data acquisition system respectively. The light source system, the optical path system, and the endoscope probe are connected in sequence. The data acquisition system is connected to the endoscope probe and the data reconstruction system respectively. The control system is used to generate timing pulse signals and control the light source system, the optical path system and the data acquisition system according to the timing pulse signals. The light source system is used to respond to the timing pulse signal, generate a pulsed laser beam of a preset wavelength, convert the pulsed laser beam into linearly polarized light, and emit it. The optical path system includes a hollow servo motor and a half-wave plate. The hollow servo motor is used to respond to the timing pulse signal and control the half-wave plate to rotate four preset angles to adjust the polarization angle of the linearly polarized light. The endoscope probe is used to process the light beam emitted from the half-wave plate, transmit the processed light beam to the sample, receive the photoacoustic signal fed back by the sample, and convert it into an electrical signal. The data acquisition system is used to respond to the timing pulse signal, acquire the electrical signal, process the electrical signal, and transmit the processed electrical signal to the data reconstruction system; The data reconstruction system is used to generate sample images based on the received processed electrical signals; The four preset angles include 0°, 22.5°, 45° and 67.5°, and the polarization angles include 0°, 45°, 90° and 135°. The optical path system also includes an optical fiber coupler and an optical fiber collimator. The optical fiber coupler and the optical fiber collimator are used to couple and collimate the linearly polarized light into the optical fiber. Correspondingly, the hollow servo motor is used to control the half-wave plate to rotate between the four preset angles and adjust the polarization angle of the linearly polarized light in the optical fiber. Generating sample images involves using photoacoustic signals at different polarization angles of 0°, 45°, 90°, and 135° to decompose the photoacoustic signals into polarization-dependent and polarization-independent components, defined as follows: ； in: It is a photoacoustic signal at a polarization angle θ. It is a polarization-dependent photoacoustic signal component. It is a photoacoustic signal component that is independent of polarization; Calculate polarization contrast: ； Polarization contrast reflects the changes in photoacoustic response of a sample at different polarization angles and quantitatively describes the anisotropic characteristics of the sample. For each polarization angle of the photoacoustic signal Image reconstruction is performed using the time-delay and summation method: ； in: It is the reconstruction intensity corresponding to position r. It is a weighting function. It is signal i at the corresponding time The value; After obtaining images at different polarization angles, a composite image is obtained through a polarization spectral fusion algorithm: ； in: It is a weighting factor for the polarization angle, based on the polarization contrast. Dynamic adjustments are made to enhance regions with significant polarization characteristics. The endoscope probe includes a MEMS scanning micromirror, a focusing lens, a rod lens assembly, an objective lens assembly, a transducer, and an ultrasonic transducer, all housed within the endoscope housing. The MEMS scanning micromirror is used to rapidly modulate and switch the beam emitted from the half-wave plate to adjust the beam path and intensity. The focusing lens is used to focus the beam output from the MEMS scanning micromirror, and the optical parameters of the focusing lens are determined based on the characteristics of the sample. The rod lens assembly is used to adjust the propagation direction and shape of the beam output from the focusing lens. The objective lens assembly is used to perform secondary focusing on the beam output from the rod lens assembly. The transducer transmits the beam output from the objective lens assembly to the sample and receives the photoacoustic signal fed back from the sample. The ultrasonic transducer converts the photoacoustic signal into an electrical signal. The focusing lens is an aspherical lens, the rod lens group includes several rod lenses arranged at equal intervals and with multiple coatings, the objective lens group includes several objective lenses with multiple coatings and anti-reflective coatings, and the endoscope shell has a double-layer structure, with the inner layer being a flexible material and the outer layer being a rigid structure. The sample is placed in a sample pool, which provides a dynamic environment for the sample through the flow of a fluid medium. The sample pool is also equipped with a temperature detection unit and a pressure detection unit, which provide different experimental environments for the sample based on the detection data of the temperature detection unit and the pressure detection unit, respectively.

2. The photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning according to claim 1, characterized in that, The light source system includes a 1200 nm pulsed laser and a linear polarizer. The 1200 nm pulsed laser is used to generate a pulsed laser beam with a wavelength of 1200 nm in response to a timing pulse signal, and the linear polarizer is used to convert the pulsed laser beam into linearly polarized light.

3. The photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning according to claim 1 or 2, characterized in that, The data reconstruction system is also used to analyze the sample image and quantify the optical properties of the sample in different directions. The control system is also used to adjust the timing pulse signal according to the optical properties in order to adjust the parameters of the pulsed laser beam.

4. The photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning according to claim 1 or 2, characterized in that, The endoscope probe, the data acquisition system, and the data reconstruction system are connected via a high-speed data transmission interface.

5. The photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning according to claim 1 or 2, characterized in that, The input end of the data acquisition system is also connected to a signal amplifier and a shock-absorbing bracket for fixing the signal amplifier. The signal amplifier is used to amplify the electrical signal and output it to the data acquisition system.

6. A photoacoustic endoscopic imaging method based on polarized light multi-angle rotation scanning, implemented based on the photoacoustic endoscopic imaging system based on polarized light multi-angle rotation scanning as described in any one of claims 1-5, comprising: In response to a timing pulse signal, a pulsed laser beam of a preset wavelength is generated, and the pulsed laser beam is converted into linearly polarized light and emitted. The polarization angle of the linearly polarized light is adjusted by using a half-wave plate that switches between four preset angles; The beam emitted from the half-wave plate is processed, and the processed beam is transmitted to the sample. The photoacoustic signal fed back by the sample is received and converted into an electrical signal. In response to the timing pulse signal, the electrical signal is acquired, processed, and analyzed to generate a sample image; The four preset angles include 0°, 22.5°, 45° and 67.5°, and the polarization angles include 0°, 45°, 90° and 135°. The optical path system also includes an optical fiber coupler and an optical fiber collimator. The optical fiber coupler and the optical fiber collimator are used to couple and collimate the linearly polarized light into the optical fiber. Correspondingly, the hollow servo motor is used to control the half-wave plate to rotate between the four preset angles and adjust the polarization angle of the linearly polarized light in the optical fiber. Generating sample images involves using photoacoustic signals at different polarization angles of 0°, 45°, 90°, and 135° to decompose the photoacoustic signals into polarization-dependent and polarization-independent components, defined as follows: ； in: It is a photoacoustic signal at a polarization angle θ. It is a polarization-dependent photoacoustic signal component. It is a photoacoustic signal component that is independent of polarization; Calculate polarization contrast: ； Polarization contrast reflects the changes in photoacoustic response of a sample at different polarization angles and quantitatively describes the anisotropic characteristics of the sample. For each polarization angle of the photoacoustic signal Image reconstruction is performed using the time-delay and summation method: ； in: It is the reconstruction intensity corresponding to position r. It is a weighting function. It is signal i at the corresponding time The value; After obtaining images at different polarization angles, a composite image is obtained through a polarization spectral fusion algorithm: ； in: It is a weighting factor for the polarization angle, based on the polarization contrast. Dynamic adjustments are made to enhance regions with significant polarization characteristics.

Images